Illuminating device

ABSTRACT

An illuminating device has light means for generating light and a light-emitter comprising an after-glowing material for emitting light after the light means is switched off or has extinguished. According to the invention, the light-emitter comprises a predetermined pattern for displaying information. Preferably, the intensity Ilm of the light emitted by the light means as compared to the intensity Ile of the light emitted by the light-emitter is such that Ile/Ilm&lt;0.1, preferably Ile/Iim&lt;00.1. Preferably, the pattern comprises an alphanumerical character, a logo and/or an arrow. The light-emitter is preferably provided on an electric lamp, on the light emission window of a luminaire or on a display window of a display device. The pattern remains visible after the light means has been switched off or has extinguished.

The invention relates to an illuminating device comprising light meansfor generating light and a light-emitter comprising an after-glowingmaterial for emitting light after the light means is switched off or hasextinguished.

In addition, the invention relates to an electric lamp comprising a lampvessel provided with the light-emitter.

The invention further relates to a luminaire comprising a housing havinga light-emission window, the housing or the light-emission window beingprovided with the light-emitter.

The invention further relates to an automotive head lamp comprising ahousing having a light emission window, the housing or thelight-emission window being provided with the light-emitter.

The invention also relates to a display device comprising a displaywindow provided with the light-emitter.

Such illuminating devices are known per se. They are applied, interalia, in so-called luminous signs, among other things, for advertisingpurposes, e.g. in shops, hotels, airports, etc. They can also be used inguiding boards as “exit”signs, in billboards, traffic lights, systemsfor guiding traffic flows and as (dashboard) lighting in vehicles. Theycan also be applied in automotive head lamps. Said illuminating devicesare used both as interior lighting and exterior lighting.

An illuminating device of the kind mentioned in the opening paragraph isknown from the English abstract of JP-A 11 73 804. The knownilluminating device comprises a luminous light-emission layer formed on(the lens body of) a vehicle headlamp. After the headlight has beenswitched off, the light-emission layer comprises a luminous pigment withan after-glowing effect.

It is an object of the invention to improve the usability of theilluminating device. According to the invention, an illumination deviceof the kind mentioned in the opening paragraph is for this purposecharacterized in that the light-emitter comprises a predeterminedpattern for displaying information.

The inventors have had the insight that the light-emitter provided onthe illuminating device can be shaped in the form of a pattern. Theafter-glowing material is applied to the illuminating device such that apredetermined pattern is obtained. The pattern is shaped such thatinformation is displayed. The after-glowing material employs the lightemitted by the light means (e.g. an electric lamp) or by another(natural) light source to activate the after-glowing effect. Inaddition, the light means may be the light emitted by (an imagedisplayed on) a display device. The predetermined pattern remainsvisible for a certain amount of time after the power to the light meansof the illuminating device has been switched off.

When the current supply to the light means is interrupted, for examplein the case of a power failure caused by a calamity, or when part of thelight means breaks down, for example when a filament bums through, orwhen the light means is turned off, the room in which the illuminatingdevice is mounted, darkens. When such darkening is undesirable, forinstance in case of an emergency, such darkening may lead to panicreactions and the persons having difficulty in finding their way in thedark, in particular when they have to leave the room. When the lightmeans is shut down, visible light will still be emitted, due to theaction of the after-glowing material. By shaping the light-emitter in apattern valuable information can be displayed, for instance informationindicating the emergency exits.

An additional advantage of a light-emitter comprising a predeterminedpattern is that after switching off the light means, informationlocalizing and/or identifying the object can be made visible, forinstance the after-glowing material is shaped to form the brand or tradename of a company. This may for instance be important in order tolocalize the illuminating device in the darkened room.

A preferred embodiment of the illuminating device according to theinvention is characterized in that the pattern comprises analphanumerical character, a logo and/or an arrow. The pattern in whichthe after-glowing material is formed on the illuminating device may be,by way of example, a safety message, a logo and/or an arrow.

Preferably, the after-glowing material comprises a photo-luminescent orphosphorescent material.

The light-emitter may be visible when the light means is operational. Inan alternative embodiment, the light-emitter becomes visible when thelight means are switched off or when there is a general power failure. Apreferred embodiment of the illuminating device according to theinvention is characterized in that the intensity I_(lm) of the lightemitted by the light means as compared to the intensity I_(le) of thelight emitted by the light-emitter is such that I_(le)/I_(lm)<0.5. Inthis embodiment, the light-emitter is visible on the illuminating devicewhen the light means is in operation, although at a relatively lowlevel. Preferably, I_(le)/I_(lm)<0.1. In this case the light-emitter ispractically invisible when the light means is in operation. This is anadvantageous embodiment in the event that the illuminating device is adisplay device provided with a light-emitter on the display screen.

An alternatively preferred embodiment of the illuminating deviceaccording to the invention is characterized in that the initial lightoutput following the switching off or the extinguishing of the lightmeans is lower than 3 cd/m². The initial light output of thelight-emitter is such that the light-emitter is visible on theilluminating device when the light means is in operation, although at arelatively low level. Preferably, the initial light output is equal toor is lower than 1 cd/m². This is an advantageous embodiment in theevent that the illuminating device is a display device provided with alight-emitter on the display screen.

The invention, in addition, relates to an electric lamp comprising alamp vessel provided with a light-emitter as described hereinbefore. Anytype of electric lamp may be employed in the illuminating device.

The invention further relates to a luminaire comprising a housing havinga light-emission window, the housing or the light-emission window beingprovided with a light-emitter as described hereinbefore.

The invention further relates to an automotive head lamp comprising ahousing having a light emission window, the housing or thelight-emission window provided with a light-emitter as describedhereinbefore.

The invention also relates to a display device comprising a displaywindow, the display window being provided with a light-emitter asdescribed hereinbefore.

The invention will now be explained in more detail with reference to anumber of embodiments and a drawing, in which:

FIG. 1 shows a low-pressure mercury vapor discharge lamp provided with alight-emitter according to the invention;

FIG. 2 shows a luminaire with a light-emission window provided with alight-emitter according to the invention, and FIG. 3 shows a displaydevice with a display window provided with a light-emitter according tothe invention.

The Figures are purely diagrammatic and not drawn true to scale. Somedimensions are particularly strongly exaggerated for reasons of clarity.Equivalent components have been given the same reference numerals asmuch as possible in the Figures.

FIG. 1 shows diagrammatically a low-pressure mercury discharge lamp 1with an elongate glass discharge vessel 3, in this example a so-called36 W TLD lamp with a diameter=25.4 mm ( 8/8inch) and length=1.20 m. Thedischarge lamp comprises an electrode 5 at each end, which electrode isformed by a tungsten incandescent coil 6 supported by conducting leadwires 7, 9 which extend through a glass pinch 11 which is provided on aglass stem 10. The incandescent coil 6 is provided with an emittermaterial such as oxides of barium, calcium, and strontium for reducingthe work function of the electrode. The stem 10 hermetically seals offthe discharge vessel 3. The lead wires 7, 9 are connected to pin-typecontacts 13 in the respective end caps 12 which are provided at eitherend of the lamp 1. The discharge vessel 3 is filled with a rare gasmixture comprising one or several of the gases xenon, krypton, argon,and neon under a certain filling pressure. The discharge vessel 3 isfurther provided with a sufficient quantity of mercury. According to theinvention, the discharge vessel is provided with a light-emitter 21comprising a predetermined pattern. Preferably, the pattern comprises analphanumerical character, a logo and/or an arrow. The pattern in whichthe after-glowing material is formed on the illuminating device may be,by way of example, a safety message (e.g. a warning), a logo (e.g. abrand name, a vignette of an organization promoting safety or promotingenvironmental issues) and/or an arrow (e.g. indicating an escape route).In the example of FIG. 1, the light-emitter comprises an arrow and theword “EXIT”.

Preferably, the intensity of the after-glowing material is such that thelight-emitter is visible on the illuminating device when the light meansis in operation. In that case the intensity I_(lm) of the light emittedby the light means as compared to the intensity I_(le) of the lightemitted by the light-emitter is such that I_(le)/I_(lm)<0.5, preferably,I_(le)/I_(lm)<0.1.

Preferably, the after-glowing material comprises a photo-luminescent orphosphorescent material. A suitable material is, for instance, acommercially available single component silicone with after-glowingproperties, such as Yfestos®. Such a material can be applied easily toobtain a predetermined pattern. Other materials to be applied are thewell-know fluorescence materials. The after-glowing material can beexposed to light having a wavelength range of approximately 350-450 nm.The wavelength range in which the after-glowing material, preferably,emits is 475-575 nm.

FIG. 2 shows diagrammatically a luminaire 21 with a light-emissionwindow 22 provided with a light-emitter 21 according to the invention.In the example of FIG. 2 the luminaire comprises a low-pressure mercuryvapor discharge lamp 1 and the light-emitter 21 according to theinvention comprises a predetermined pattern comprising an arrow and a(company) logo.

FIG. 3 shows very diagrammatically a display device 31 with a displaywindow 32 provided with a light-emitter 21 according to the invention.In the example of FIG. 3 the light-emitter 21 comprises a predeterminedpattern comprising a (brand) name. In particular in the case of displaydevice 31 provided with a light-emitter according to the invention, thelight-emitter is preferably, practically invisible when the displaydevice is in operation. In that case the intensity I_(lm) of the lightemitted by the light means as compared to the intensity I_(le) of thelight emitted by the light-emitter is such that I_(le)/I_(lm)<00.5.

The scope of the invention is not limited to the embodiments. Theinvention is embodied in each new characteristic and each combination ofcharacteristics. Any reference sign do not limit the scope of theclaims. The word “comprising” does not exclude the presence of otherelements or steps than those listed in a claim. Use of the word “a” or“an” preceding an element does not exclude the presence of a pluralityof such elements.

1. An illuminating device comprising light means for generating lightand a light-emitter comprising an after-glowing material for emittinglight after the light means is switched off or has extinguished,characterized in that the light-emitter comprises a predeterminedpattern for displaying information.
 2. An illuminating device as claimedin claim 1, characterized in that the intensity I_(lm) of the lightemitted. by the light means as compared to the intensity I_(le) of thelight emitted by the light-emitter is such that I_(le)/I_(lm)<0.5.
 3. Anilluminating device as claimed in claim 2, characterized in thatI_(le)/I_(lm)<0.1.
 4. An illuminating device as claimed in claim 1,characterized in that the initial light output following the switchingoff or the extinguishing of the light means is lower than 3 cd/m².
 5. Anilluminating device as claimed in claim 4, characterized in that theinitial light output is equal to or lower than 1 cd/m².
 6. Anilluminating device as claimed in claim 1, characterized in that thepattern comprises an alphanumerical character, a logo and/or an arrow.7. An illuminating device as claimed in claim 1, characterized in thatthe after-glowing material comprises a photo-luminescent orphosphorescent material.
 8. Electric lamp comprising a lamp vesselprovided with a light-emitter according to claim
 1. 9. Luminairecomprising a housing having a light emission window, the housing or thelight-emission window being provided with a light-emitter according toclaim
 1. 10. Automotive head lamp comprising a housing having a lightemission window, the housing or the light-emission window being providedwith a light-emitter according to claim
 1. 11. Display device comprisinga display window provided with a light-emitter according to claim 1.